We're going to begin with a staggering figure. 500 million. That's how much value stocks have lost on wall street in just the last three days. Yesterday alone, the average 401(k) LOST MORE THAN $1,300. So, what exactly is going on? Weekend "gma" anchor, bianna golodryga, here with answers. Good morning, bianna. Reporter: What an ugly day tuesday was. The third-worst day of the year for the dow. It lost 243 points. One reason, lower-than-expected profits at some big companies, INCLUDING 3M AND DuPONT, U.P.S. And caterpillar. Companies are increasingly worried about china's economy slowing down, as well as the presidential election here at home and the looming fiscal cliff. But there is good news in all of this. Facebook's stock is soaring again this morning, after the company reported a big jump in mobile advertising sales. Josh, the bottom line is, there is a lot of uncertainty out there right now. As we know, the markets don't like uncertainty. Something to keep our eyes on in the coming weeks. New details on the deadly

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